Oil cooler having protective and control means



B. BURNS July 25,, 1944.

OIL COOLER HAVING PROTECTIVE AND CONTROL MEANS Filed July 27, 1942 Z'Sheets-Sheet l INVENTOR July 25, 1944.

OIL COOLER HAVING PROTECTIVE AND CONTROL MEANS B. BURNS 4 Filed July 27, 1942 542/65 flue/vs,

INVENTOR A'ITORNEY umrso STATE ?ateuted July 25, 1944 s PATENT or ies assists on. cooum navmc mornc'rrvn AND common mans Bruce Burns, Los Angeles, Calif auignor to The Garrett Corporation, Airesearch Mannhctnring Company division, Los Angeles, Call! a corporation of California Application July 27,1942, Serial No. 452,447

4 Claims.

This invention relates in general to oil cooling systems for internal combustion engines, and rethe hot oil supply piping and the return piping oi the oil circulating system.

A further object of the invention is to provide a protective valve structure which has the character of a separate unit, the installation of which requires a minimumoi machining of the houspressure changes in accordance with varying conditions. It is an object of the invention to rovide in conjunction with a heat exchanger in an oil cooling system of the class described. means which will automatically close at least the inlet opening of the heat exchanger when a heavy pressure is built up in, or a heavy pressure surge occurs in the oil circulating system.

It is an object of .the invention to provide an oil cooling device which has oil flow control valve parts associated with the inlet and outlet openings of the cooler, and has cooperating parts which are actuated by oil pressure applied in the oil circulating system, the cooperating valve parts of the device functioning as the result of automatic response to prescribed high pressure conditions to prevent the flow of oil into the in: terior of the heat exchanger through either the inlet or the outlet openings of the heat exchanger. Accordingly, the invention n'ot only provides a protective device for use with coolers other than the ones specifically disclosed herein,

'but will enable reduction in the weight of oil coolers now, employed in aircraft, this reduction in weight being made possible by the fact that where the invention is employed the bursting strength. of the cooler may be reduced, and the protective mechanism may be adjusted so, as to prevent from reaching the interior of the cooler any pressure which might be close to the pressure limits established for the cooler.

An object of the invention is to provide in an oil cooler a protective device which .will be actuated by a pressure in the oil circulating system not greatly in excess of the maximum normal operating pressure, and will protect the heat exchanger or core from any higher pressure which may be produced in. the oil circulating system.

A further object of the invention is to provide jing of the protective and control unit.

In oil cooling devices of the type now generally employed with aircraft engines, the heat exchanger element comprises both a cooler proper having a chamber usually of cylindrical shape through which refrigerant air is passed in tubes arranged parallel to the axis ofthe chamber and a cylindrical shell encircling the cooler to provide a warm up jacket or mud through which oil may be selectively passed with respect to the cooler proper when oilin the lubricating system .is cold at the time the engineis started or when due to imperfect temperature regulation, the oil passages of the cooler have become obstructed by coatings of congealed oil on the air tubes.

It is an object of this invention to provide a cooler having a muff which forms a warm up passagesubstantially surrounding and in series relationship with the cooler core so that during operation the cooler is at all times subiect to the warming action of the hot-oil flowing through the warm-up passage.

It is another object of the invention to provide means protecting the muff from pressures of destructive value in the return piping which carries the cooled 011 back to the engine. Excessive pressures in the muff mayeither act outwardly to burst the outer wall of the mufl or inwardly to crush the wall of the cooler.

Other objects and purposes of the invention will appear from a reading of the following 'description and drawings.

Referring to the drawings which are for illustrative purposes only, t

Fig. l is an elevational view of a cooling device embodying the invention, showing the protective and control unit in vertical section.

Fig.2 is an enlarged sectional view taken as indicated by the line 2-2 of Fig. 1.

Fig. 3 is a section taken as indicated by the line a protective unit which may be readily secured to the fitting of the heat exchanger containing Iv the inlet and outlet openings therefor, and which unit has inlet and-outlet ports for connection to 'heat exchanger -I having anouter cylindrlc shell or drum it surrounded by a warm-up reservoir 2 assgscs or mull The chamber of the drum, in keeping with known practices, is provided with rei'rigerant air tubes (not shown) around which the oil is caused to circulate by means oi" suitably disposed bailie plates (not shown). The upper ends of the mufl are spaced apart to receive a fitting I2, the walls of which are formed to provide four chambers l3, l4, l and IS. The chamber l3 forms a communicating connection between the hot oil delivery pipe I! and one end of the mufl' I The chamber |5 receives oil from the other end of the mufl. Chambers l4 and I6 communicate with the inlet and outlet openings respectively of the cooler l9. The upper wall of the fitting I2 is formed with ports l6, l9, and 29 for the chambers l4, l5, and I6 respectively.

A protective control unit generally. designated by the numeral 2| comprises a housing having exterior and suitably located partition walls to provide a row of chambers 22, 23, and 24 having ports 25, 26,'and 21. registering with the ports l9, l9, and 29 respectively of the chambers oi the fitting |2. Between a horizontal partition wall 29 and the upper wall or the protective unit lies the chamber 29 extending across and above all three 01' the chambers'22, 23, and 24. This chamber 29 communicates with the chambers 23 and 24 below it through ports 39 and 3| respectively in the wall 29. Oil in the chamber 29 is re-- turned to the engine through theport 32 and the cooled oil return piping 33.

opening Q5 and which also serves as a protective cover for the parts of the valve assembly 44.

The valve cage 45 has, adjacent its inner end. ports 52 through which oil may flow from the interior chamber of the valve cage into the chamber 36. A valve stem 53 has mounted upon it a piston 54 which may reciprocate in sliding engagement with the bore surface oi the valve cage 49. This piston may be of any suitable design and may be secured to the valve stem in any suitable manner. As shown in the drawings, it comprises a cup 55, a washer 56, and packing 51 held between the cup and washer and it is secured to the valve stem by means of a nut 59 threaded upon the-stem and arranged to clamp the cup and washer against a stepped shoulder on the valve stem.

The chambers 23 and 22 are connected at their rear sides by a communicating passageway 34, as shown in Fig. 3. This passageway is provided by means of a chambered rearwardly extending projection 35 of the housing 2|. The passageway 34 is divided by a partition wall 36 of the housing into an inlet chamber 31 and an outlet chamber 39 connected by a circular opening 39 in the wall 36.

Flow of oil from the mull through chambers l5 and 23 to the chamber 29 is controlled by a check valve assembly 49 mounted in the upper wall of the housing 2|, and weighted by a spring 42. Outward flow of oil from the cooler drum I9 through the chambers l6 and 24 to the chamber 29 is controlled by a similarly mounted check valve assembly -4| which is weighted by a spring Flow of oil through the passageway 34 from the mufl and chambers l5 and 23 to chambers 22 and I4, and thence into the oil cooling drum I9, is controlled by a valve assembly insert 44, which is shown in Fig. 3 of the drawings. The side wall of the housing 2| has an opening through which the valve assembly insert 44 may be installed. 4

The valve assembly has a cylindrical member or valve cage 46 which, with its associated parts, is inserted through the .opening 45, its inner end fitting .within the opening 39 in the wall 36 and its outer end portion snugly engaging a portion 45a of reduced diameter of the opening 45. The inner end of the cage 46 is step-shouldered at 41 for abutting engagement with a correspondingly formed shoulder in the opening 39 to limit-inward movement of the cage and form a fluid tight joint with the wall 36. The outer end portion or the cage 46 is formed with an annular flange 49 which similarly engages the ,outer wall of the reduced portion 45:: of the opening 45, a gasket 49 being disposed between the flange 49 and the housing to iorm a fluid tight joint. The valve cage 46 is held in position by a nut 5| which has threaded engagement with the bore of the cooler |9, as indicated by arrows A centrally bored inwardly extending boss 59 of the end nut 5| holds a guide sleeve 5|a for the outer end of the valve stem 53. The inner end of the valve stem 53 carries a valve 69 which may bemoved outwardly when oil pressure upon the inner face of the piston 54 causes the piston and valve stem to move outwardly against the pressure of a spring 6|,iwhich engages the-nut 5| and the outer face of the piston 54 at its respective ends. .An outward movement of the piston under the pressure 0! oil causes the valve 69 to engage the inner end of the valve cage 46 which forms a valve seat for the valve 69. A ring 62 of spring wire limits inward movement of the piston 54 and valve 69.

The oil from the engine enters the muii l I from the hot oil delivery piping I! through the chamber |3 in the fitting l2 and after passing through the chamber of the,mufl or completely around the drum M, as indicated by arrows I9 in Figs. -1 and 5, is delivered to the protective unit 2| through the chamber l5 of the fitting l2 through ports I 9 and 26 into the inlet chamber 23 of the protective unit. Normally oil flows from the chamber 23 past the open valve 69 of valve structure 44 in passageway 34 through the cooler inlet chamber 22 and thence into and through the From the cooler, the oil flows through the chambers 29 and 24, liftingthe valve 42 and passing through the unit outlet chamber 29 into the return piping 33 as indicated by the arrows I2.

The spring 6| associated with the valve structure 44, Fig. 3, is of such strength that it will resist valve closing movement of the piston 54 against the fluid pressure in the chambers 23 and 31 somewhat greater than the normal operating pressure of the circulating system, but considerably less than the maximum safe working pressure of thecooler drum l9. Should heavy pressure be built up'in the chambers 23 and 31, such pressure will be transmitted to the inner face of the piston 54, causing the piston 54 to move outward or leftward against the force of the spring 6|. The valve 69 will be thereby moved toward the inner end of the valve cage 46, and as the valve 69 approaches the valve seat formed by the inner end 01? the cage, the friction of oil passing through the reduced space between the valve periphery and the valve seat, together with the pressure exerted against the rightward face of the valve 69, will move the valve 69 into contacting engagement with the valve seat, thereby cutting 01! communication between the mui! and the cooling drum II. This closing of the' I valve 69 occurs when a prescribed increase in pressure is developed in thehot oil delivery piping and mum. The pressure 01 fluid thereafter delivered through the hot oil piping I! may increase dangerously above the pressure required to operate the valve II, but cannot be transmitted through the passageway It to the cooling chamber within the drum- II.

The spring 42 of the check valve structure ill between the chamber 23 and the outlet chamber a is gauged so that the valve thereof will yield chamber II and return piping l3, bypassing the assess:

cooling chamber within the drum Ill and return- 'ing directly to the engine.

The spring 0, associated with the check valve structure ll, yield upwardly, opening the port 3| in response to a relatively small pressure drop between the chambers 24 and 2!. On the other hand, any increase in pressure in the chambe:- "above that in the chamber 24,, however slight, will allow the spring 43 to close the port 8|, giving assurance when a high pressure surge is transmitted to the chamber 28 from the return piping the valve of the check valve structure ll will close the port ll, protecting the oil cooler against destructive pressures existing at any point beyond the outlet port 32 of the protective and control unit 2|.

The check valve structure 40 similarly protects the muff H from excessive pressures in the return piping 33. The check valve structure It therefore has the dual purpose of opening a bypass for the oil around the cooler when, due to a high pressure in the delivery piping system or due to stoppage within the cooler, it is of advantage to break the connection between the delivery piping system and the cooler, and also of. protecting the mull. from excessive oil pressure in the return piping. x

The cooler is protected from high pressure in the delivery piping by the valve assembly 4! and from high pressure in the return piping by check valve structure ll.

As schematically shown in Fig.5, in a cooling device constructed in accordance with this invention, the oil from the engine, which is always warm after a few moments following the starting of the engine, passes through the muff H in a position of heat exchange relation with the drum III. This passage of warm oil around the cooling drum is a condition which obtains at all times whether the valve assembly 44 is in'open or closed position, excepting only those times when the bypass valve structure 40 and the valve structure ll are both closed, a situation which will obtain only for brief intervals of time when back pressure surges develop in the return pipin The cooler is thus subjected. to the warming action of the drum whether or not oil is passing through the cooler. This is a desirable feature of the invention. When the oil flowing through i the cooler is being unduly cooled by the refrigerant, the mull prevents loss of heat from the oil in the cooler checking the temperature drop and inhibiting waxing of the oil. 7 when the oil passing through the cooler. is at too high a tem perature, a portion of the heat passing from the oil in the muff to that in the cooler is readily absorbed by the refrigerant air and the rise in temperature heat has no very serious effect on the en ine.

when the oil is stationary .within the cooler drum l'\ due to the opening of the bypass valve ll between the mufl and the returnpiping, the cooler is still subject to the warming action of the muff. If the opening of the bypass is occasioned by congealing of oil within the cooler, the heat of the muff will accomplish a melting of the congealed oil more quickly than otherwise. Similarly, if the bypass is opened because of a heavy pressure drop through the cooler due to the high viscosity of cold oil within it, the heat from the mull will warm the oil within the cooler. The arrangement by which the mufl is in series with either the cooler or the cooler bypass, and the disposition of the valve controls as has been described, provide thatthe cooler is under substantialiy all conditions warmed by hot oil flow-' ing through the muff, that both the cooler and the mull are protected from pressure surges in the return piping, that the cooler is protected from high pressures in the delivery piping, and that the muif is provided witha safety relief from excessively high pressures in the delivery piping. I

I claim as my invention:

1. In a protective device for connecting to the hot oil delivery piping and the cooled oil return piping of an oil cooling system, a heat exchanger having a cooling chamber with an inlet opening and air outlet opening, said protective device having inlet passage means connecting said delivery piping to said inlet opening, outlet passage means connecting said retum'piping to said outlet opening, bypass passage means connecting said inlet passage means with said outlet passage means and bypass valve means for said bypass passage means operating in response to excess pressure in said inlet passage means to permit a flow through said bypass passage means .to said outlet passage means, said inlet passage means comprising walls forming a restricted first I circular opening intermediate its ends, and a second circular opening connecting with the outside the interior' space of said inlet passage means downstream from said first opening, said second opening being axially aligned with said first opening and being of a diameter at least equal to that of said first opening, a protective valve assembly for installation from the outside through said second opening, comprising in combination: a hollow cylinder open at its inner end, having a fluid tight engagement with the walls of said openings and formed with a port intermediate its ends and downstream from said first opening; a valve stem in said cylinder projecting inwardly from the open end of said cylinder; a piston on said valve stem slidably engaging the bore surface of said cylinder outwardly from said port; stop means limiting inward movement of said piston toward said port; means resiliently urging said piston toward'said stop means; a valve on the inner end of said stem of a diameter not greater than the outside diameter of said cylinder for closing the inner end of said cylinder; and means'for securing said cylinder against longitudinal movement with respect to said openings.

2. In a protective device for connecting to the hot oildelivery piping and 'the cooled oil return piping of an oil cooling system, a heat exchanger having a cooling chamber with an inlet opening and an outlet opening, said protective device having inlet passage means connecting said deoi' the oil due to anyunabsorbed livery piping to said inlet opening, outlet passage ,means connecting said return piping to said outoutlet passage means, said inlet passage means comprising walls forming a restricted first circular opening intermediate its ends, and a second circular opening connecting with the outside the let chamber respectively and a port connecting said upper chamber with said return piping; a

interior space of said inlet passage means downstream from said first opening, said second opening being axially aligned with said first opening and being of a diameter at least equal to that of said first opening, a protective valve assembly .for installation from the outside through said second opening, comprising in combination: a hollow cylinder open at its inner end, having a fluid tight engagement with the walls of said openings and formed with a port intermediate its ends and downstream from said first opening; a valve stem in said cylinderprojecting inwardly from the open end of said cylinder; a piston on said valve stem slidably engaging the bore surface of said cylinder outwardly from said port; stop means limiting inward movement oi said piston toward said port; stop means fixing the position of said cylinder inwardly of said openings; a removable closure means for said second opening fixing the position of said cylinder outwardly of said openings; a coiled spring on said valve stem acting between said closure means and said piston; and a valve on the inner-end of said stem of a diameter not greater than the outside diameter of said cylinder for closing the inner end of said cylinder, said spring yielding to excessive fiuid pressures on the inner face of said piston to close said valve.

3. In a protective device fitting for connecting to the hot oil delivery piping and the cooled oil return piping of an oil cooling system, a heat exchanger assembly having a cooler with an inlet port and an outlet port and having a port connected to the delivery piping, said ports beingarranged in alignment substantially in the same plane in an upper exterior wall of said assembly, the combination of walls formed to provide in the lower portion of the fitting a cooler inlet chamber, a cooler outlet chamber and a delivery piping chamber, said three chambers being aligned in juxtaposition with and having port communication with said inlet port, outlet port and delivery port respectively and formed to provide further an elongated upper chamber above and across said three chambers, a first port and a second port connecting saidupper chamber with said delivery piping chamber and said cooler outlaterally projectlng wall structure providing in conjunction with said walls a passageway at the rear of said three aligned chambers connecting said delivery piping chamber with ,said cooler inlet chamberand providing a transverse wall in said passageway having a first opening, one end wall of said wall structure being formed with a second opening axially aligned with said transverse wall opening; a spring weighted normally open check valve structure supported in and sealing said second opening for closing said first opening in response to excessive pressures in said passageway; a normally closed check valve structure supported in an opening in the upper wall of said upper chamber for opening said first port in response to excessive pressure in said delivery piping chamber; and a check valve structure supported in an opening in the upper wall of said upper chamber for closing said second port in response to a reverse pressure drop across said second port.

4. In a protective unit for connecting to the hot oil delivery piping and a cooled 011 return piping of an oil cooling system, a heat exchanger having a cooler with an inlet and an outlet, the combination of: a housing-having walls providing a unit inlet chamber for connection to said delivery piping, a cooler inlet chamber for connection to said cooler inlet, a cooler outlet chamber for connection to said cooler outlet, a'passageway connecting said cooler inlet and cooler outlet chambers, a unit outlet chamber for connection to said return piping, at least one wall of each of said passageway and said unit outlet chamber being an exterior wall of said unit, a first port between said unit inlet chamber and said unit outlet chamber, a second port between said cooler outlet and said unit outlet chambers; a check valve structure mounted in an exterior wall-of said passageway having a normally open valve .for closing said passageway, and a spring weighted piston responsive to excessive oil pressure in said passageway to'move said valve to close said passageway; a check valve structure mounted in the exterior wall of said unit outlet chamber having a normally closed relatively heavily spring weighted valve for openingsaid first port in responseto excessive pressure in said unit inlet chamber; and a check valvestructure mounted in the exterior wall of said housing having a relatively lightly spring weighted valve for closing said second port in response to a reversely acting pressure differential between said unit outlet chamber and said cooler outlet chamber.

BRUCE BURNS. 

